Bridge construction



Dec. 1 1959 I Filed April 7. 1954 A. HOYDEN ETAL 2,914,783

BRIDGE CONSTRUCTION 2 Sheets-Sheet l 1 M I I, 1 x I k it i' 1 N \ir'; 2

INVENTORS ADOLF HOYDE/V HEINRICH HESS ATTORNEYS Dec. 1, 1959 A. HOYDENETAL 2,91 3

BRIDGE CONSTRUCTION Filed April 7, 1954 z Sheets-Sheet 2 IN VENTOR$ADOLF HOYDEN .sion bridge that carries the entire horizontal force.

United States Patent 2,914,783 BRIDGE CONSTRUCTION Adolf Hoyden andHeinrich Hess, Oberlrausen, Sterlu'ade, I Germany, assignors toGutehoffnungshutte Sterkrade Aktiengesellschaft, Oberhausen, Rhineland,Germany Application April 7, 1954, Serial No. 421,648 Claims priority,application Germany April 10, 1953 8 Claims. (Cl. 14--21) The presentinvention relates broadly to the art of bridge construction.

More particularly this invention relates to construction of suspensionbridges and is further concerned with a method and apparatus forbuilding a partly anchored suspension bridge or a suspension bridge thatis rigid in itself.

The invention is particularly concerned with the anchoring of thesuspension cables at the opposite ends of the bridge.

The construction of a ground anchored suspension bridge is dependentupon the provision of a sufficiently firm foundation for the abutmentsbecause the abutments must Withstand the entire and generally largepulling force exerted by the supporting cables. In this foundationstructure and in order to transmit the horizontal components thatrepresent a considerable part of the pulling force of the cable totheground, it occasionally arises, that a sliding post or coifer foundationis required.

Furthermore, in cases in which it is not possible to directly anchor thesupporting cables in the ground or to a connection that resists push andpull, usually special abutment bodies, thus preferably an anchorage innatural rock, there has been provided an abutment body of such dead orinherent weight that the same, diminished by the vertically upwardlydirected component of the cable pull, is sufficient to create on thefoundation the necessary friction for opposing the horizontal componentof the cable pull. The cable ends in this type arrangement are usuallytrained about what is termed a reversing bearing or cable saddle andextend in. a steeper direction or angle downwardly and are anchored inthe respective abutment bodies. In this connection it has been proposedto construct the anchoring body as a tiltable body and arrive at anarrangement in the nature of a lever-arm structure propped thestiffening girders for the bridge.

The present invention is concerned with systems for transmitting atleast a part of the horizontal component of force resulting from thepull of the cable to the stiifening girders of partly anchoredsuspension bridges aswell as ones that are fully rigid, that is asuspen- Such types of construction are of great practical importance forit frequently happens that the ground conditions are not suited for thebuilding of a ground anchored suspension bridge, even if specialcounter-weight bodies ,are used.

The known bridge arrangements along the aforementioned lines suffer fromcertain defects On the one hand, if the abutments are constructed aswhat are termed tiltable abutments and include uniform counterweightrnasses, changeable traflic loads on the bridge ice will result in upand down motions of the roadbed on the bridge. On the other hand, it hadpreviously been necessary, in connection with facilitating theconstruction of the stiffening girders and for erection of the bridgesuperstructure, to arrange joints adjacent the bridge openings which dueto the transmission of the horizontal force had to be large and heavy.

It is therefore an object of the present invention to eliminate theaforementioned defects and to provide for simple and expeditiousconstruction of a fully anchored or partly anchored and stiffenedsuspension bridge in a manner which Will eliminate or materiallydiminish the necessity for assembling scaffolds in the middle opening.

Accordingly the invention has for an object to provide a method in theconstruction of suspension bridges in which during the assembly ofthe'bridge the horizontal force of the supporting cables, depending uponthe arbitrary selected reversing angle of the cables, is borne by meansof special components termed push or pull members which provide atemporary ground anchoring system whereupon by a subsequent removal oryielding of the push or pull members the horizontal force of the cableis partly or wholly transmitted to the stiffening girders. 1

Another object the invention provides, for the accomplishment of theaforestated method of transmitting horizontal cable forces, a laterallymovable force transmitting body that is supported in or on thestationary foundation and movable in the direction of the horizontalcomponents of force generated by the cables.

As a particular object this aforementioned body is of pistol shape incross section.

Consistent with the aforestated objects and in order to temporarilyaccommodate the whole or any arbitrary portion of the horizontal forceof the cables between the slidable pistol shaped body and the foundationthe invention provides adjustable supporting means operable to maintainthe movable pistol body out of contact with the horizontal girders orsupporting structure of the bridge until such time as it is desired thatthe horizontal components of force developed by the cables in theiranchoring be transmitted to the horizontal girders or bridge supports.

As a specific object the supporting means are adjustable and in thisconnection the adjustability further comprehends an arrangement in whichthe supporting means can be removed and additionally includes theprovision of adjustable anchoring cables between the horizontallymovable body and the fixed or stable foundation.

In the latter instance the invention provides an arrangement in whichthe suspension cables can be anchored in the horizontally movable bodyeither in a direct line as regards the downward inclination from thetowers or at a larger angle of inclination by an arrangement which willinclude cable bends.

' Other and more specific objects and advantages of the presentinvention will become apparent from the following description of severalembodiments of the invention as illustrated diagrammatically in theaccompanying drawing. The drawings omit all structural parts that arenot necessary for complete understanding of this invention.

In the drawings, Figurel is a fragmentary side elevation of a suspensionbridge,

Figure 2 is a top plan view of the arrangement shown in Figure 1,

Figure 3 is an enlarged scale sectional view taken on line 33 of Figure2, H

Figure 4 is a view similar to Figure 3 and illustrating a modificationutilizing tensionable members in temporary ground anchoring, and

Figure is a view similar to Figure 4 and of a slightly modified form ofthe invention in which the suspension cables are not provided with cablebends adjacent their lower ends.

In the arrangement illustrated in Figures 1 and '3, the supportingcables 1 of the suspension bridge are suspended over towers T andanchored in a foundation body 2. This foundation body 2 is of a castconcrete structure that is firmly embedded in the ground. Means areprovided for putting a bend in the suspension cables so that they extendat a steeper angle within the foundation body than the angle formed withthe horizontal at the upper level of the bridge. The foundation body 2has a socket or recess in the upper part thereof that is open upwardlyand within this socket is mounted a substantially smaller concrete body3 of the general shape of a pistol. This concrete body 3 is supported ona group of bearings as at 31 and a further bearing arrangement at 32 andis thus slidably mounted for movement in the direction of the horizontalcomponent of force generated by the suspension cables. The movableconcrete body 3 bears against contact bearings 4 provided on thestillening girders 5 when the bridge is completed.

The guiding of the suspension cables 1 includes training the samethrough special guiding or bearing means 6, a cable saddle of knownconstruction and supporting these bearing means by means of rollingcontact bearing members 66 on an upper angular surface 13 of theconcrete body 3. This upper angular surface 13- is perpendicular to theline xx which bisects the angle formed by the bend in the cables as theypass over saddles 6. Further, the foundation body 2 includes a lowerangular surface 12 that is parallel with the surface 13. The movableconcrete body 3 includes another angular surface 13' that is spaced fromand parallel with the surfaces 13 and 12. Between the surfaces 12 and 13which are perpendicular to the bisector line xx are mounted adjustablespacer or bracing members 7. These bracing members 7 are removable oradjustable so as to control the spacing between surfaces 12 and 13'. Thespacer or bracer members 7 have been diagrammatically illustrated asjack means. Conventional hydraulic or screw action jacks can beutilized, also devices known in the mining art as pit props can beinterposed between the surfaces 12 and 13. Further, the inventioncontemplates shims or any other means which can exert a pushing forceagainst the bodies 3 to hold the same stationary relative to the end ofthe girders 5 until it is desired to release said holding force. Thecable ends, as is conventional, are separated into their individualstrands and in the recess 8 provided in the foundation body 2 they areconnected to an adjusting anchor support 9. In this support body 9 thecables, as required, may be tensioned or slackened. The details of thecable anchoring so that they may be tensioned or slackened are not shownbut any arrangement well known in the art for this purpose could beutilized. During assembly of the superstructure cables, which aretemporarily ground anchored in the member 9, the pistol 3 is preventedfrom movement to the right in the figure by the bracing members 7. Thusthe horizontally movable body or pistol 3 is supported on its rollingcontact bearing members 31, 32 and the side bearings 4 on the horizontalgirders have not yet been contacted by the pistol so that the stifieninggirders '5, which at that stage of construction are still in the processof assembly, are not as yet subjected to any horizontal components offorce generated by the cables. At the proper time, that is, when thehorizontal girders 5 and the superstructure is completed, the bracingmembers or elements 7 are shortened or entirely removed so that thepistol or movable body 3 can slide toward the right on bearing members31, 32 and thus through bearing elements 4 can exert horizontal pressureagainst the completed girders 5. The portion of the horizontal forceexerted on the girders 5 depends on the angle of bend of the cables andthus can be arbitrarily determined. In a ground anchoring arrangement inwhich the cables are anchored without any bends therein there is nohorizontal component or force generated and in a ground anchoringarrangement in which the cables are vertical in their anchoring relationthe horizontal pressure equals the entire horizontal component of forceof the cable pull. The latter instance would concern a suspension bridgethat is fully braced. Between these two limits, that is, the zero limitand the fully braced limit, there are various possibilities of partlyanchored suspension bridge systems. An important consideration whichmust be borne in mind in this connection embodies the intentionaldistribution of the force that has to be resisted by the foundation bodyduring temporary anchoring in the ground. These forces are considerablylower in a system including temporary anchoring than one in which thecables were permanently anchored in the ground initially, since in thelatter instance during completion of the bridge, until any horizontalforce is transmitted to the stiffening girders, a considerable part ofthe bridge weight, that is, roadway, rails and all trafiic loads arelacking.

In other words, by the present invention the bridge cables are anchoredand the horizontal component of force generated thereby is resisted bythe bracing of the movable body 3 to retain that body immovable untilnecessary. The superstructure, rails, roadways and the like are embodiedin the bridge and when these components have been completed, then, byshortening or removing the bracing members 7, the horizontal componentof force generated by the anchored cables is transmitted to the girders5 to stiffen the bridge. In order to allow for expansion and contractionmovements occasioned by changes in temperature, the cable guide blockconstruction at 6 is supported on rolling contact bearing members 66 andthe ends of the horizontal girders are further supported on rollingcontact bearing members 55.

Therefore as regards Figure 3, the invention provides a method andapparatus for, in effect, storing a horizontal component of force duringcompletion of a suspension bridge and then applying that force to thehorizontal components of the bridge to rigidity the bridge.

In the arrangement of Figure 4, the movable concrete body 3' is largerand heavier. Additionally, it is provided with a recess 8 within whichthe anchoring supports 9 for the cables 1 are arranged. In thismodification, the cables 1 after passing over cable saddles 6 areanchored in the pistol or movable body 3' which in turn is supported ona set of rolling contact bearing members 31' and is anchored by means ofadjustable cables 10 extending between the interior of the recess 8 anda recess 8 provided in the foundation body 2. During the assembly of thebridge the cables 10 are tensioned to such an extent that the movablebody or pistol 3 does not bear against the bearings 4 on the stifieninggirders 5. It is only when the bridge structure is substantiallycompleted that the cables 10 are slackened so that, as in the case inthe arrangement of Figure 3, the body 3' moves to the right to transmita predetermined portion of the horizontal component of force to thegirders 5.

In Figure 5 is illustrated a further embodiment in which the anchoringcables 1 are anchored to a cable support 9 mounted in a recess 8 withoutbeing bent over a cable guide block. Otherwise the structural componentsare identical with that form shown in Figure 4 and includes thesupporting bearings 31'. In the arrangement of Figure 5 the specialanchoring cables 10 are tightened so that the concrete body 3 is heldfrom movement to the right until such time as desired whereupon thecables 10 are the anchored cables to the girders.

.slackened' and the concrete body 3 moves to the right to 'applyflhehorizontal force to the girders 5.

, It is further to be pointed out that the angular relationship to thehorizontal of the anchoring cables is not to be limited to theparticular direction shown in Figures 4 and 5. These cables 10 mayextend at a greater or less inclination to the horizontal. In thisconnection, however, care should be taken that the vertical force orcable pull is balanced unless the dead weight of the concrete body orpistol suflices'therefore.

; It is thus clear that this invention provides an anchorarrangementincludes means for subsequently releasing the temporary anchoring withthe ground or foundation so as to transmit the horizontal components offorce of the cable pull to the horizontal stiffeners or girders of thebridge to increase the stability thereof.

It is believed clear that from the arrangement of Figures 3 to 5 thesystem includes a laterally movable concrete body that is supported onrolling contact bearing members. In Figure 3, adjustable bracing meansprevent lateral movement of this body in a direction toward the bridgeuntil this movement is desired, whereas in Figures 4 and 5 additionalcable means or hold backs prevent this transmission of force.

With all embodiments before mentioned the supporting cables 1 of thesuspension bridge are anchored on both ends in the same manner. Thereare two foundation bodies 2 on the abutment points of the river banks,each body provided with the special characteristics illustrated in theforms of invention shown in Figures 3 to 5.

It is therefore to be particularly pointed out that the inventionembodies an improvement in bridge construction relating to bridges ofthe type having horizontal girders and supporting cables which includesinitially anchoring the ends of the cables in a fashion to preventtransference of any horizontal components of force developed by theanchored cables to the girders so that the assembly of the bridge, thatis, completion thereof, may be accomplished and subsequently andindependently of the anchoring of the cables the method comprehendstransferring at least a part of the horizontal components of forcedeveloped by I In accomplishing the aforementioned improvement, theinvention includes interposing a movable force transmitting elementbetween anchored cables having bends therein and the girders of thebridge. Furthermore, the invention includes the application of force inopposition to the horizontal component of force developed by theanchored cables until such time as it is desired to apply thishorizontal component of force to the girders to stiffen the same.

What is claimed is:

l. The method of applying horizontal force to an end of roadwaystiffening girders in a suspension bridge in which the stiffeninggirders are suspended from suspension cables and in which one end ofeach stiffening girder is freely supported on a foundation body,comprising positioning a horizontally movable body on said foundationbody, said horizontally movable body having an end portion adapted tocontact the one end of each stiffening girder and being in supportingcontact with the corresponding end portion of the suspension cableswhereby the horizontal component of force of the cable pull is exertedon said movable body, applying a force between said movable body and thefoundation body to hold said' movable body out of contact with saidstiffening girders until they are ready to be stressed and releasingsaid force to allow movement of said movable body to apply said cablepull component to the end of said stiffening girders.

2. The method of applying horizontal force to each end of roadwaystiffening girders in a suspension bridge comprising constructing spacedfoundation bodies, suspending stiifening girders from suspension cableswith the opposite ends of the girders freely supported on saidfoundation bodies, positioning a horizontally movable body on eachfoundation body outwards of the adjacent ends of the girders insupporting contact with the corresponding end portions of the suspensioncables and with an end portion of each movable body in a position tomake contact with the respective adjacent ends of the girders wherebythe horizontal component of force of the cable pull is exerted on saidmovable bodies, applying a force between each movable body andfoundation body to hold the end portions of the movable bodies out ofcontact with the ends of the stiffening girders until they are ready tobe stressed and releasing said force to allow movement of saidhorizontally movable bodies towards the ends of the girders to contactthe respective end portions of the movable bodies with the opposite endsof the girders so that said horizontal component of force of the cablepull is applied to the ends of the stiffening girders.

3. In a suspension bridge including a foundation body at each end of thebridge, roadway stiffening girders, and suspension cables suspendingsaid stiffening girders, means for applying horizontal force to at leastone end of said girders, said means including a horizontally movablebody supported on at least one foundation body, one end of eachstiffening girder being freely supported on said foundation body, saidhorizontally movable body having an end portion adapted to contact saidone end of each stiffening girder, means establishing a supportingcontact between said horizontally movable body and the corresponding endportion of the suspension cables whereby the horizontal component offorce of the cable pull is exerted on said horizontally movable body,and means for releasably applying a force between said horizontallymovable body and the foundation body to hold said movable body out ofcontact with said stiffening girders until they are ready to bestressed, whereupon a releasing of said force will allow movement ofsaid horizontally movable body so as to apply said cable pull componentof force to said one end of said stiffening girders via said end pontionof the horizontally movable body.

4. A suspension bridge including a primary anchoring foundation embeddedon opposite sides of the space to be spanned, cable supporting towermeans intermediate said foundations, a secondary foundation bodysupported on each primary foundation for horizontal movement thereon,each secondary body having an abutment means on the side thereof facingsaid tower means, longitudinally extending girder means arranged betweenthe foundations, said abutment means being adapted to engage the ends ofthe girder means, supporting cable means suspended over said tower meansand including opposite anchored ends, means suspending said girder meansfrom said supporting cable means, said secondary foundation bodies beingin supporting contact with the correspond- 5. A suspension bridge asclaimed in claim 4 in which I said last-mentioned means compriseadditional cable means adjustably connected between the primaryanchoring foundations and respective secondary foundation bodies toexert a pulling force on said secondary bodies in a direction away fromsaid girder means.

6. A suspension bridge as claimed in claim 4 and said last-mentionedmeans comprising means arranged between said primary foundations andsaid secondary bodies on the side of the secondary bodies that isadjacent the ends of the girder means for exerting a pushing force onsaid secondary bodies.

7, A suspension bridge as claimed in claim 4 and bearing meansinterposed between the respective primary anchoring foundations andsecondary foundation bodies and said bearing means havingfoundation-engaging surfaces constituted by surfaces of revolution.

8. A suspension bridges as claimed in claim 4 and cable guide meansmounted on said secondary foundation bodies for changing the angle ofbend of the cable means so that they extend at a steeper inclination tothe horizontal, said primary foundations and said secondary foundationbodies having respective facing surfaces extending per pendicular to aline that bisects the angle of bend of the 8 cables, and the meansarranged between each foundation and each secondary body for preventingmovement of the respective bodies comprising bracing means extendingbetween said facing surfaces.

References Cited in the file of this patent UNITED STATES PATENTS(Addition to No. 738,768)

OTHER REFERENCES Civil Engineering, April 1939, pages 217-220.

